The present invention relates generally to surgical apparatus, and more particularly to a novel guide or jig for safe and accurate placement of fixation screws across a sacroiliac joint.
Fractures of the pelvis are potentially life-threatening. Injuries to the sacroiliac joints frequently require stabilization with screws. This has been accomplished in the past only through extensive surgical dissection and by blindly passing screws across the sacroiliac joint into the sacrum. This procedure creates a substantial risk of perforating the spinal cord, the bowel, an artery or a vein. The present invention provides a jig that safely and accurately guides fixation screws across a sacroiliac joint.
The sacrum is the large triangular bone at the base of the spine. It is made up of five vertebrae and their intervertebral discs which have fused together. The much smaller coccyx, sometimes called the tailbone, consists of three to five rudimentary vertebrae and attaches to the bottom of the sacrum to form the bottom tip of the spine. The sacroiliac joints are the mostly vertical joints where the two sides of the sacrum attach to the two ilia, or hip bones, also called pelvic bones. The ilia and their wings help form a bottom supporting structure for the internal organs and provide a pair of attachment points for the femurs or uppermost large leg bones.
The contacting surfaces of the sacrum and each ilium are covered with cartilage and fit closely together, allowing only a minimum of movement. A small synovial cavity is present between them. In later years of life, the two surfaces may actually attach. The sacrum and ilia are held together by an elaborate system of ligaments, comprising both short ligaments across the two sacroiliac joints and various longer ligaments attaching various points on the sacrum to more distant points on the ilia.
Various traumas can stretch or tear the attaching ligaments and loosen one or both of the sacroiliac joints. The most obvious result of such an injury is that movement, particularly up and down movement, can then occur along one of the joints so that a leg on that side becomes effectively shorter during walking, often about 1 inch.
When the injury to a sacroiliac joint is sufficiently severe, the joint must be repaired by fixation with surgical screws inserted across the joint. As stated earlier, this requires extensive surgical dissection. Even with extensive surgical dissection, the position of the sacrum and sacroiliac joint is difficult to accurately ascertain as a fixation screw is blindly passed through an ilium. This creates a substantial risk of perforating the spinal cord, the bowel, an artery or a vein.
It is seen, therefore, that there is a need for a guide or jig that will safely and accurately guide fixation screws across the sacroiliac joint.
It is, therefore, a principal object of the present invention to provide a safe and accurate guide for placing fixation screws across the sacroiliac joint into the sacrum.
It is a feature of the present invention that it is simple and straightforward to use.
It is an advantage of the present invention that it involves much less tissue cutting and other trauma to a patient than prior art methods.